The IRS was prepared to require tax filers to indicate on line 61 whether they and their family had health coverage during 2016. If not, taxpayers are subject to a penalty.

Under federal rules, anyone who receives an insurance subsidy must file a tax return to verify that the person was eligible and received the proper amount of financial assistance based on household income.  There is the risk of loss of health insurance subsidies for failure to file tax return.

The "Cadillac Tax" is a 40% penalty (excise tax) on health insurance plans and a provision of the Affordable Care Act that takes effect on January 1, 2018.

The Affordable Care Act is part health law, part tax law.  

The NIIT applies at a rate of 3.8% to certain net investment income of individuals, estates and trusts that have income above the statutory threshold amounts.